Optical laminate, polarizing plate using same, surface plate, and image display device

ABSTRACT

Provided is an optical laminate capable of suppressing deterioration of visibility in a high-temperature environment. The optical laminate comprises a layer comprising a metal oxide on a plastic film, wherein the emissivity of the optical laminate for light with a wavelength range of 2000 nm or more and 22000 nm or less is 0.27 or more and 0.75 or less as measured from the side of the layer comprising a metal oxide with respect to the plastic film.

TECHNICAL FIELD

The present disclosure relates to an optical laminate, and a polarizingplate, a surface plate and an image display device each using theoptical laminate.

BACKGROUND ART

In recent years, image display devices such as liquid crystal displaydevices and organic EL display devices have found their way into a widerrange of applications, and used for smartphones, car navigation systems,televisions, monitors, digital cameras, and the like.

Among image display devices, car navigation systems are often installedin the dashboards of automobiles. Portable image display devices such assmartphones are also often carried in automobiles.

In the middle of summer, the interior of an automobile is subjected tohigh temperature, and in particular, the temperature of a dashboard mayreach nearly 80° C. Thus, an image display device may be exposed to hightemperature in the automobile for a long time, and in such a case, thereis a risk of deterioration of various kinds of performance of the imagedisplay device.

As means for suppressing a rise in temperature of the interior of anautomobile, laminated glass having a heat wire shielding structure hasbeen proposed (e.g. Patent Literature 1).

CITATION LIST Patent Literature

-   PTL 1: WO 2019/167897

SUMMARY OF INVENTION Technical Problem

When the laminated glass of Patent Literature 1 is used as window glassof an automobile, a rise in temperature of the interior of theautomobile can be suppressed to a certain degree. However, in anautomobile with no measures taken for suppressing a rise in temperature,an image display device is exposed to high temperature.

For this reason, laminated glass as in Patent Literature 1 may be usedas protection glass for an image display device.

However, when an image display device for which laminated glass as inPatent Literature 1 is used as protection glass is exposed to ahigh-temperature environment, a problem of deterioration of visibilityof the image display device frequently occurs. When laminated glass asin Patent Literature 1 is used as protection glass for an image displaydevice, there is also a problem of increase in the thickness.

The present disclosure has been made in view of these circumstances, andan object of the present disclosure is to provide an optical laminatecapable of suppressing deterioration of visibility in a high-temperatureenvironment, and a polarizing plate, a surface plate and an imagedisplay device each using the optical laminate.

Solution to Problem

The present disclosure provides the following [1] to [4].

[1] An optical laminate, comprising a layer comprising a metal oxide ona plastic film, wherein an emissivity of the optical laminate for lightwith a wavelength range of 2000 nm or more and 22000 nm or less is 0.27or more and 0.75 or less as measured from a side of the layer comprisinga metal oxide with respect to the plastic film.[2] A polarizing plate comprising: a polarizer; a first transparentprotection plate disposed on one side of the polarizer; and a secondtransparent protection plate disposed on the other side of thepolarizer, wherein at least one selected from the group consisting ofthe first transparent protection plate and the second transparentprotection plate is the optical laminate according to [1].[3] A surface plate for an image display device, comprising the opticallaminate according to [1] bonded onto a resin plate or a glass plate.[4] An image display device comprising the optical laminate according to[1] on a light emission surface of a display element.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide anoptical laminate capable of suppressing deterioration of visibility in ahigh-temperature environment, and a polarizing plate, a surface plateand an image display device each using the optical laminate.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a schematic sectional view showing an embodiment of an opticallaminate of the present disclosure.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of an optical laminate of the presentdisclosure, and a polarizing plate, a surface plate and an image displaydevice each using the optical laminate will be described.

[Optical Laminate]

The optical laminate of the present disclosure comprises a layercomprising a metal oxide on a plastic film, wherein the emissivity ofthe optical laminate for light with a wavelength range of 2000 nm ormore and 22000 nm or less is 0.27 or more and 0.75 or less as measuredfrom the side of the layer comprising a metal oxide with respect to theplastic film.

In the present specification, the emissivity of the optical laminate forlight with a wavelength range of 2000 nm or more and 22000 nm or less asmeasured from the side of the layer comprising a metal oxide withrespect to the plastic film is sometimes referred to as “emissivity α”.

The emissivity means a relative value of the energy of light emitted byan object through heat emission against the energy of light emitted by ablackbody at the same temperature, which is defined as 1.

FIG. 1 is a schematic sectional view showing an embodiment of theoptical laminate of the present disclosure.

An optical laminate 100 of FIG. 1 comprises a layer 30 comprising ametal oxide on a plastic film 10. The optical laminate 100 of FIG. 1comprises a functional layer α (20) between the plastic film 10 and thelayer 30 comprising a metal oxide. The functional layer α (20) of FIG. 1is a single-layered hardcoat layer 21. The optical laminate 100 of FIG.1 comprises a functional layer β (40) on a side opposite to the plasticfilm 10 with respect to the layer 30 comprising a metal oxide. Thefunctional layer β (40) of FIG. 1 is a single-layered low refractiveindex layer 41.

<Plastic Film>

The plastic film is a support for a layer comprising a metal oxide and afunctional layer as described later.

Supports other than the plastic film include glass. Glass is itselfexcellent in heat resistance, but is likely to retain heat because ithas a large thickness. The thickness of glass is typically 0.5 mm ormore. Thus, when glass is used as a support, there is a problem that theoptical laminate is likely to be subjected to high temperature in ahigh-temperature environment, and layers forming the optical laminate,such as a layer comprising a metal oxide and a functional layer, orconstituent members of an image display device, such as a displayelement are affected by the high temperature, so that visibility islikely to be deteriorated.

Examples of the plastic film include those formed from one or moreselected from the group consisting of polyester, triacetyl cellulose(TAC), cellulose diacetate, cellulose acetate butylate, polyamide,polyimide, polyether sulfone, polysulfone, polypropylene,polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, polymethyl methacrylate, polycarbonate, polyurethane, amorphousolefin (cyclo-olefin-polymer: COP) and the like. The plastic film may beone obtained by co-extruding two or more resins, or one obtained bylaminating two or more plastic films.

Among these plastic films, stretched films, particularly biaxiallystretched films, of polyesters such as polyethylene terephthalate andpolyethylene naphthalate are preferable in that they are excellent inmechanical strength and dimensional stability. Polyimide is preferablein that it has good flex resistance, and is easily applied to a foldableimage display device and a rollable image display device. Plastic filmsobtained by co-extruding polycarbonate and polymethyl methacrylate arepreferable in that they have good moldability.

As a substrate of the optical laminate, a thin glass film having athickness of 5 μm or more and 200 μm or less can be used instead of aplastic film. In recent years, thin glass films have attracted attentionas, for example, thin glass films for foldable image display. When athin glass film is used, the smoothness of the optical laminate isimproved, so that it can be expected that the emissivity decreases andpenetration of heat is suppressed, and further, improvement of opticalproperties can be expected.

Among the plastic films, plastic films having a retardation value of3000 nm or more and 30000 nm or less or plastic films having a ¼wavelength phase difference are suitable in that it is possible toprevent observation of unevenness with different colors on a displayscreen when an image is observed through polarized sunglasses.

The plastic film may be one subjected to known easy-adhesion treatmentsuch as corona discharge treatment, primer treatment or surfacepreparation.

For handleability and suppression of deformation by heat, the thicknessof the plastic film is preferably 5 μm or more, more preferably 10 μm ormore, further preferably 25 μm or more.

On the other hand, if the thickness of the plastic film is excessivelylarge, the plastic film may retain heat, leading to exertion of aharmful effect on visibility. If the plastic film retains heat,deterioration of visibility may persist for a long time because thetemperature is unlikely to be lowered even by moving the opticallaminate from a high-temperature environment to a normal-temperatureenvironment. Thus, the thickness of the plastic film is preferably 350μm or less, more preferably 150 μm or less, further preferably 90 μm orless, still further preferably 70 μm or less.

The thickness of the plastic film is preferably in the range of 5 μm ormore and 350 μm or less, 5 μm or more and 150 μm or less, 5 μm or moreand 90 μm or less, 5 μm or more and 70 μm or less, 10 μm or more and 350μm or less, 10 μm or more and 150 μm or less, 10 μm or more and 90 μm orless, 10 μm or more and 70 μm or less, 25 μm or more and 350 μm or less,25 μm or more and 150 μm or less, 25 μm or more and 90 μm or less, or 25μm or more and 70 μm or less.

The thickness of each of layers forming the optical laminate, such asthe plastic film, the layer comprising a metal oxide and the functionallayer can be calculated from an average value at randomly selected 20points on a picture of a cross-section of the optical laminate underscanning electron microscope (SEM) or a scanning transmission electronmicroscope (STEM). It is to be noted that the 20 portions are selectedwithout focusing on certain locations.

The accelerating voltage and the magnification in STEM may be setdepending on a layer to be measured.

<Layer Comprising Metal Oxide>

The layer comprising a metal oxide is a layer which plays a key role forsetting the emissivity α of the optical laminate within a rangedescribed later.

Examples of the metal oxide include indium tin oxide (ITO); antimonyoxide such as antimony trioxide, antimony doped tin oxide (ATO) andantimony pentaoxide; tin oxide; zinc oxide such as aluminum doped zincoxide and gallium doped zinc oxide; and titanium oxide, and the layerpreferably comprises one or more selected from the group consisting ofthese metal oxides.

Among the above-described metal oxides, ITO is preferable in that theemissivity α of the optical laminate is easily set within the rangedescribed later. In addition, ITO is preferable in that the refractiveindex of the layer comprising a metal oxide can be increased, andtherefore the reflectance of the optical laminate in a visible lightregion is easily reduced by combination with an optionally formed lowrefractive index layer. In addition, ITO is preferable in that it hasgood transparency and high conductivity, so that it is easy for theoptical laminate to have a good antistatic property.

For heat dissipation materials such as metal nitrides such as aluminumnitride and boron nitride which are commonly used as heat dissipationmaterials for heatsinks, it is difficult to set the emissivity to 0.75or less.

For metals such as Au, Ag, Cu and Al which are exemplified in PatentLiterature 1, it is difficult to set the emissivity to 0.27 or more, sothat transparency may be deteriorated. The metals have a low refractiveindex, so that it is difficult to set the refractive index of the layercomprising a metal oxide within a range described later. The mirrorreflection of the metals is so strong that backgrounds are reflected,resulting in deterioration of visibility. A deposited film of Ag has amigration problem.

Examples of embodiments comprising the layer comprising a metal oxideinclude the following (1) and (2):

(1) a layer comprising metal oxide particles and a binder resin; and(2) a metal oxide film obtained by depositing a metal oxide by aphysical vapor deposition method such as sputtering or a chemical vapordeposition method.

The above (1) is preferable in that it has better flex resistance overthe above (2), and is easily applied to a foldable image display deviceand a rollable image display device.

<<(1) Layer Comprising Metal Oxide Particles and Binder Resin>> —MetalOxide Particles—

Examples of the metal oxide particles include indium tin oxide (ITO)particles; antimony oxide particles such as particles of antimonytrioxide, antimony doped tin oxide (ATO) and antimony pentaoxide; tinoxide particles; zinc oxide particles such as particles of aluminumdoped zinc oxide and gallium doped zinc oxide; and titanium oxideparticles, and the layer preferably comprises one or more types ofparticles selected from the group consisting of these types of metaloxide particles, and more preferably comprises ITO particles.

The average particle size of the metal oxide particles is preferably 2nm or more and 200 nm or less, more preferably 7 nm or more and 100 nmor less, further preferably 8 nm or more and 80 nm or less, stillfurther preferably 10 nm or more and 50 nm or less.

The average particle size of the metal oxide particles is preferably inthe range of 2 nm or more and 200 nm or less, 2 nm or more and 100 nm orless, 2 nm or more and 80 nm or less, 2 nm or more and 50 nm or less, 7nm or more and 200 nm or less, 7 nm or more and 100 nm or less, 7 nm ormore and 80 nm or less, 7 nm or more and 50 nm or less, 8 nm or more and200 nm or less, 8 nm or more and 100 nm or less, 8 nm or more and 80 nmor less, 8 nm or more and 50 nm or less, 10 nm or more and 200 nm orless, 10 nm or more and 100 nm or less, 10 nm or more and 80 nm or less,10 nm or more and 50 nm or less.

In the present specification, the average particle size of each type ofparticles can be calculated by the following operations (1) to (3):

(1) a cross-section of the optical laminate is imaged by STEM, where theaccelerating voltage is preferably 10 kV or more and 30 kV or less andthe magnification is preferably 50000 times or more and 300000 times orless.(2) 10 particles are randomly extracted on an observation image, and theparticle sizes of the individual particles are then calculated, where across-section of the particle is sandwiched between arbitrary twoparallel straight lines, the two straight lines are combined so as tomaximize the distance between the two straight lines, and the distancebetween the two straight lines is measured as a particle size; and(3) the observation image of the same sample is subjected to the sameoperation as above five times on different screens, and a value obtainedfrom the number average for a total of 50 particles is then determinedas an average particle size of the particles.

The content of the metal oxide particles is preferably 150 parts by massor more, more preferably 250 parts by mass or more, further preferably400 parts by mass or more, based on 100 parts by mass of the binderresin. When the content of the metal oxide particles is 150 parts bymass or more, the emissivity α of the optical laminate can be easily setto 0.75 or less. The content of high refractive index metal oxideparticles such as ITO particles is preferably 150 parts by mass or morein that the refractive index of the layer comprising a metal oxide isincreased, so that the reflectance of the optical laminate in a visiblelight region can be reduced by combination with an optionally formed lowrefractive index layer.

The content of the metal oxide particles is preferably 2000 parts bymass or less, more preferably 1500 parts by mass or less, furtherpreferably 1200 parts by mass or less, still further preferably 1000parts by mass or less, based on 100 parts by mass of the binder resin.When the content of the metal oxide particles is 2000 parts by mass orless, deterioration of coating film strength of the layer comprising ametal oxide can be easily suppressed. If the emissivity α of the opticallaminate is excessively low, heat generated in an image display deviceis unlikely to be released to the outside. The content of the metaloxide particles is preferably 2000 parts by mass or less for preventingthe emissivity α of the optical laminate from becoming excessively low.

The content of the metal oxide particles based on 100 parts by mass ofthe binder resin is preferably in the range of 150 parts by mass or moreand 2000 parts by mass or less, 150 parts by mass or more and 1500 partsby mass or less, 150 parts by mass or more and 1200 parts by mass orless, 150 parts by mass or more and 1000 parts by mass or less, 250parts by mass or more and 2000 parts by mass or less, 250 parts by massor more and 1500 parts by mass or less, 250 parts by mass or more and1200 parts by mass or less, 250 parts by mass or more and 1000 parts bymass or less, 400 parts by mass or more and 2000 parts by mass or less,400 parts by mass or more and 1500 parts by mass or less, 400 parts bymass or more and 1200 parts by mass or less, or 400 parts by mass ormore and 1000 parts by mass or less.

—Silane Coupling Agent—

The layer comprising metal oxide particles and a binder resin preferablycomprises a silane coupling agent. The silane coupling agent may be asilane coupling agent as a surface treatment agent for the metal oxideparticles, or a silane coupling agent as a binder resin.

When the metal oxide particles are subjected to surface treatment with asilane coupling agent, the affinity of the metal oxide particles to thebinder resin is improved, so that the metal oxide particles are likelyto be uniformly dispersed.

A case where the layer comprises a silane coupling agent as a binderresin is also preferable in that the metal oxide particles are likely tobe uniformly dispersed.

Examples of the silane coupling agent include3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldiethoxysilane,3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-glycidoxypropylmethyldlimethoxysilane,3-glycidoxypropyltrimethoxysilane,3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane,N-2-(aminoethyyl)-3-aminopropylmethyldlimethoxysilane,N-2-(aminoethy0-3-aminopropyltrimethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine,N-phenyl-3-aminopropyltrimethoxysilane,tris-(trimethoxysilylpropyOisocyanurate,3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane,3-isocyanatepropyltriethoxysilane, methyltrimethoxysilane,dimethyldlimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane,dimethyldlimethoxysilane, phenyltrimethoxysilane,n-propyltrimethoxysilane, n-propyltriethoxysilane,hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane,decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane,trifluoropropyltrimethoxysilane, vinyltrimethoxysilane andvinyltriethoxysilane. In particular, one or more selected from the groupconsisting of 3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldiethoxysilane and3-methacryloxypropyltriethoxysilane are preferably used.

—Binder Resin—

The binder resin preferably comprises a cured product of a curable resincomposition. Examples of the cured product of a curable resincomposition include a cured product of a thermosetting resincomposition, and a cured product of an ionizing radiation-curable resincomposition, and a cured product of an ionizing radiation-curable resincomposition is preferable for obtaining good mechanical strength.

The ratio of the cured product of the curable resin composition to thetotal binder resin of the layer comprising metal oxide particles ispreferably 50 mass % or more, more preferably 70 mass % or more, furtherpreferably 90 mass % or more, still further preferably 100 mass %.

The thermosetting resin composition is a composition comprising at leasta thermosetting resin, and the resin composition is cured when heated.

Examples of the thermosetting resin include an acrylic resin, a urethaneresin, a phenol resin, a urea melamine resin, an epoxy resin, anunsaturated polyester resin, and a silicone resin. In the thermosettingresin composition, a curing agent is added to the curable resin ifnecessary.

The ionizing radiation-curable resin composition is a compositioncomprising a compound having an ionizing radiation-curable functionalgroup. In the present specification, the “compound having an ionizingradiation-curable functional group” is sometimes referred to as an“ionizing radiation-curable compound”. Examples of the ionizingradiation-curable functional group include ethylenically unsaturatedbond groups such as a (meth)acryloyl group, a vinyl group and an allylgroup, an epoxy group, and an oxetanyl group. The ionizingradiation-curable compound is preferably a compound having anethylenically unsaturated bond group, more preferably a compound havingtwo or more ethylenically unsaturated bond groups, and in particular, a(meth)acrylate-based compound having two or more ethylenicallyunsaturated bond groups is further preferable. As the(meth)acrylate-based compound having two or more ethylenicallyunsaturated bond groups, either a monomer or an oligomer can be used.

The ionizing radiation means an electromagnetic wave or a chargedparticle radiation which has an energy quantum capable of polymerizingor crosslinking molecules. An ultraviolet ray or an electron beam istypically used, and in addition, an electromagnetic wave such as anX-ray or a γ-ray, or a charged particle radiation such as an α-ray or anion beam can be used.

In the present specification, the (meth)acrylate means acrylate ormethacrylate, the (meth)acrylic acid means acrylic acid or methacrylicacid, and the (meth)acryloyl group means an acryloyl group or amethacryloyl group.

—Photopolymerization Initiator and Photopolymerization Accelerator—

When the ionizing radiation-curable compound is an ultravioletray-curable compound, the ionizing radiation-curable compositionpreferably comprises additives such as a photopolymerization initiatorand a photopolymerization accelerator.

Examples of the photopolymerization initiator include one or moreselected from the group consisting of acetophenone, benzophenone,α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyldimethylketal,benzoylbenzoate, α-acyloxime esters, thioxanthones and the like.

The photopolymerization accelerator is capable of increasing the curingrate by relieving inhibition of polymerization by air during curing, andexamples thereof include one or more selected from the group consistingof isoamyl p-dimethylaminobenzoate ester, ethyl p-dimethylaminobenzoateand the like.

—Diffractive Index and Film Thickness—

The diffractive index of the layer comprising metal oxide particles anda binder resin is preferably 1.53 or more and 2.30 or less, morepreferably 1.57 or more and 2.00 or less, more preferably 1.60 or moreand 1.80 or less, more preferably 1.65 or more and 1.75 or less. Whenthe refractive index of the layer comprising a metal oxide is in any ofthe above-described ranges, the reflectance of the optical laminate in avisible light region can be easily reduced by combination with anoptionally formed low refractive index layer.

The refractive index of the layer comprising metal oxide particles and abinder resin is preferably in the range of 1.53 or more and 2.30 orless, 1.53 or more and 2.00 or less, 1.53 or more and 1.80 or less, 1.53or more and 1.75 or less, 1.57 or more and 2.30 or less, 1.57 or moreand 2.00 or less, 1.57 or more and 1.80 or less, 1.57 or more and 1.75or less, 1.60 or more and 2.30 or less, 1.60 or more and 2.00 or less,1,60 or more and 1.80 or less, 1.60 or more and 1.75 or less, 1.65 ormore and 2.30 or less, 1.65 or more and 2.00 or less, 1.65 or more and1.80 or less, or 1.65 or more and 1.75 or less.

In the present specification, the refractive index of each layer means arefractive index at a wavelength of 550 nm. The refractive index of eachlayer can be herein calculated by, for example, fitting of thereflectance spectrum measured with a reflection photometer and thereflectance spectrum calculated from an optical model of a multilayerthin film using the Fresnel coefficient.

The thickness of the layer comprising metal oxide particles and a binderresin is preferably 100 nm or more, more preferably 200 nm or more,further preferably 500 nm or more, for easily setting the emissivity αto 0.75 or less.

There is limitation on reduction of the emissivity α by increasing thethickness of the layer comprising metal oxide particles and a binderresin. If the thickness of the layer comprising metal oxide particlesand a binder resin is excessively large, transparence tends to bedeteriorated. The thickness of the layer comprising metal oxideparticles and a binder resin is preferably 5.0 μm or less, morepreferably 2.0 μm or less, further preferably 1.5 μm or less, forthinning the film.

The thickness of the layer comprising metal oxide particles and a binderresin is preferably in the range of 100 nm or more and 5.0 μm or less,100 nm or more and 2.0 μm or less, 100 nm or more and 1.5 μm or less,200 nm or more and 5.0 μm or less, 200 nm or more and 2.0 μm or less,200 nm or more and 1.5 μm or less, 500 nm or more and 5.0 μm or less,500 nm or more and 2.0 μm or less, or 500 nm or more and 1.5 μm or less.

For reducing the reflectance in a visible light region by elimination ofinterference waves by combination with an optionally formed lowrefractive index layer, the thickness of the layer comprising metaloxide particles and a binder resin is preferably adjusted inconsideration of n₀ representing a refractive index of the layercomprising metal oxide particles and a binder resin. Specifically, thelayer comprising metal oxide particles and a binder resin is preferablyadjusted to a thickness close to an integral multiple of “550 nm/2n₀”.The range of the thickness of the layer comprising metal oxide particlesand a binder resin, which is adjusted to reduce the reflectance in avisible light region, varies depending on the refractive index range andtherefore is hard to define as described above, and the thickness ispreferably 120 nm or more and 750 nm or less, more preferably 130 nm ormore and 500 nm or less, further preferably 140 nm or more and 400 nm orless.

For reducing the reflectance in a visible light region, the thickness ofthe layer comprising metal oxide particles and a binder resin ispreferably in the range of 120 nm or more and 750 nm or less, 120 nm ormore and 500 nm or less, 120 nm or more and 400 nm or less, 130 nm ormore and 750 nm or less, 130 nm or more and 500 nm or less, 130 nm ormore and 400 nm or less, 140 nm or more and 750 nm or less, 140 nm ormore and 500 nm or less, or 140 nm or more and 400 nm or less.

The layer comprising metal oxide particles and a binder resin maycomprise additives such as a leveling agent, a dispersant, a dye, anultraviolet ray absorbent, a light stabilizer and an antioxidant as longas the effects of the present disclosure are not hindered.

The layer comprising metal oxide particles and a binder resin can beformed by, for example, applying a coating solution, in which componentsfor forming the layer is dispersed or dissolved, onto a plastic film orthe like, drying the applied coating solution, and then performingirradiation with an ionizing radiation if necessary.

The layer comprising metal oxide particles and a binder resin ispreferably subjected to heating treatment after the layer is formed asdescribed above. The heating treatment enables the emissivity α to beeasily reduced.

The heating treatment temperature is preferably 90° C. or higher, morepreferably 95° C. or higher, further preferably 100° C. or higher forthe lower limit, and preferably 170° C. or lower, more preferably 160°C. or lower, further preferably 150° C. or lower for the upper limit.

The heating treatment temperature is preferably 30 minutes or more, morepreferably 45 minutes or more, further preferably 50 minutes or more forthe lower limit, and preferably 200 minutes or less, more preferably 120minutes or less, further preferably 80 minutes or less for the upperlimit.

<<(2) Metal Oxide Film>>

The metal oxide film is obtained by depositing a metal oxide by, forexample, a physical vapor deposition method such as sputtering or achemical vapor deposition method. Among the metal oxide films, an indiumtin oxide film which allows the emissivity to be easily reduced ispreferable.

The metal oxide film is preferably amorphous for easily setting theemissivity α of the optical laminate to 0.27 or more. That is, the metaloxide film is preferably one that has not been subjected crystallizationtreatment by heating, such as annealing treatment. An amorphous metaloxide film is preferable in that it has good flex resistance, and iseasily applied to a foldable image display device and a rollable imagedisplay device.

For these reasons, the metal oxide film is preferably an amorphous filmof indium tin oxide.

—Refractive Index and Film Thickness—

The refractive index of the metal oxide film is preferably 2.0 or moreand 2.5 or less, more preferably 2.1 or more and 2.2 or less. When therefractive index of the metal oxide film is in any of theabove-described ranges, the reflectance of the optical laminate in avisible light region can be easily reduced by combination with anoptionally formed low refractive index layer.

The refractive index of the metal oxide film is preferably in the rangeof 2.0 or more and 2.2 or less, or 2.1 or more and 2.5 or less as wellas in any of the above-described ranges.

The thickness of the metal oxide film is preferably 10 nm or more, morepreferably 20 nm or more, further preferably 30 nm or more, for easilysetting the emissivity α to 0.75 or less. The degree to which a layerhaving a low emissivity repels out radiation heat tends to become higheras the thickness increases. Thus, the thickness of the metal oxide filmis preferably 100 nm or more for suppressing a rise in temperature ofthe optical laminate.

The transparency tends to be deteriorated if the thickness of the metaloxide film is excessively large. For thinning the film, the thickness ofthe metal oxide film is preferably 1000 nm or less, more preferably 500nm or less, further preferably 300 nm or less.

The thickness of the metal oxide film is preferably in the range of 10nm or more and 1000 nm or less, 10 nm or more and 500 nm or less, 10 nmor more and 300 nm or less, 20 nm or more and 1000 nm or less, 20 nm ormore and 500 nm or less, 20 nm or more and 300 nm or less, 30 nm or moreand 1000 nm or less, 30 nm or more and 500 nm or less, or 30 nm or moreand 300 nm or less.

For easily applying the metal oxide film to a foldable image displaydevice and a rollable image display device, the thickness of the metaloxide film is preferably 30 nm or more and 250 nm or less, morepreferably 30 nm or more and 150 nm or less.

For reducing the reflectance in a visible light region by combinationwith an optionally formed low refractive index layer, the thickness ofthe metal oxide film is preferably 100 nm or more and 200 nm or less,more preferably 100 nm or more and 170 nm or less, further preferably100 nm or more and 140 nm or less.

<Functional Layer α>

The optical laminate may comprise at least one functional layer αbetween the plastic film and the layer comprising a metal oxide.

Examples of the functional layer a include a hardcoat layer, a highrefractive index layer, a medium refractive index layer, a lowrefractive index layer, an antiglare layer, an antistatic layer, and acircular polarization layer, and a single-layered hardcoat layer ispreferable.

<<Hardcoat Layer>>

The optical laminate preferably comprises a hardcoat layer as thefunctional layer α for enhancing scratch resistance and pencil hardness.

The hardcoat layer preferably comprises a resin component. The resincomponent of the hardcoat layer preferably comprises a cured product ofa curable resin composition as a main component. The main componentmeans 50 mass % or more, preferably 70 mass % or more, more preferably90 mass % or more, further preferably 100 mass %, of the total resin ofthe hardcoat layer.

Examples of the cured product of a curable resin composition include acured product of a thermosetting resin composition, and a cured productof an ionizing radiation-curable resin composition, and a cured productof an ionizing radiation-curable resin composition is preferable forobtaining better mechanical strength.

Examples of the curable resin composition of the hardcoat layer includethe curable resin compositions exemplified for the layer comprising ametal oxide.

The hardcoat layer may comprise additives such as an ultraviolet rayabsorbent, a light stabilizer, an antioxidant and a refractive indexmodifier.

For easily obtaining good scratch resistance, the thickness of thehardcoat layer is preferably 0.1 μm or more, more preferably 0.5 μm ormore, more preferably 1.0 μm or more, more preferably 2.0 μm or more.For suppressing retention of heat and suppressing curling, the thicknessof the hardcoat layer is preferably 100 μm or less, more preferably 50μm or less, more preferably 30 μm or less, more preferably 20 μm orless, more preferably 15 μm or less, more preferably 10 μm or less.

The thickness of the hardcoat layer is preferably in the range of 0.1 μmor more and 100 μm or less, 0.1 μm or more and 50 μm or less, 0.1 μm ormore and 30 μm or less, 0.1 μm or more and 20 μm or less, 0.1 μm or moreand 15 μm or less, 0.1 μm or more and 10 μm or less, 0.5 μm or more and100 μm or less, 0.5 μm or more and 50 μm or less, 0.5 μm or more and 30μm or less, 0.5 μm or more and 20 μm or less, 0.5 μm or more and 15 μmor less, 0.5 μm or more and 10 μm or less, 1.0 μm or more and 100 μm orless, 1.0 μm or more and 50 μm or less, 1.0 μm or more and 30 μm orless, 1.0 μm or more and 20 μm or less, 1.0 μm or more and 15 μm orless, 1.0 μm or more and 10 μm or less, 2.0 μm or more and 100 μm orless, 2.0 μm or more and 50 μm or less, 2.0 μm or more and 30 μm orless, 2.0 μm or more and 20 μm or less, 2.0 μm or more and 15 μm orless, or 2.0 μm or more and 10 μm or less.

<Functional Layer β>

The optical laminate may comprise at least one functional layer β on thelayer comprising a metal oxide, side opposite to the plastic film.

Examples of the functional layer β include a low refractive index layer,a high refractive index layer, an antiglare layer, an antifouling layer,and a circular polarization layer. The functional layer may also havethe aforementioned functions. For example, the low refractive indexlayer may have an antifouling property or an antiglare property.

The total thickness of the at least one functional layer β is preferably1000 nm or less, more preferably 500 nm or less, more preferably 350 nmor less, more preferably 200 nm or less, more preferably 150 nm or less.

The temperature of the layer located on a side opposite to the plasticfilm with respect to the layer comprising a metal oxide is raised byradiation heat outside the image display device and radiation heatgenerated from the inside of the image display device and transmittedthrough the layer comprising a metal oxide. Thus, it tends to becomemore likely that the at least one functional layer β retains heat as thetotal thickness of the at least one functional layer β increases. Thus,when the total thickness of the at least one functional layer β is 350nm or less, the optical laminate can be easily inhibited from beingsubjected to high temperature. When the total thickness of the at leastone functional layer β is 350 nm or less, the emissivity α can be easilyreduced.

Given that the total thickness of the at least one functional layer β ispreferably small, the functional layer β is preferably a single layer,more preferably a single-layered low refractive index layer.

<<Low Refractive Index Layer>>

The low refractive index layer is preferably located on an outermostsurface on a side opposite to the plastic film with respect to the layercomprising a metal oxide.

The refractive index of the low refractive index layer is preferably1.10 or more and 1.48 or less, more preferably 1.20 or more and 1.45 orless, more preferably 1.26 or more and 1.40 or less, more preferably1.28 or more and 1.38 or less, more preferably 1.30 or more and 1.32 orless.

The refractive index of the low refractive index layer is preferably inthe range of 1.10 or more and 1.48 or less, 1.10 or more and 1.45 orless, 1.10 or more and 1.40 or less, 1.10 or more and 1.38 or less, 1.10or more and 1.32 or less, 1.20 or more and 1.48 or less, 1.20 or moreand 1.45 or less, 1.20 or more and 1.40 or less, 1.20 or more and 1.38or less, 1.20 or more and 1.32 or less, 1.26 or more and 1.48 or less,1.26 or more and 1.45 or less, 1.26 or more and 1.40 or less, 1.26 ormore and 1.38 or less, 1.26 or more and 1.32 or less, 1.28 or more and1.48 or less, 1.28 or more and 1.45 or less, 1.28 or more and 1.40 orless, 1.28 or more and 1.38 or less, 1.28 or more and 1.32 or less, 1.30or more and 1.48 or less, 1.30 or more and 1.45 or less, 1.30 or moreand 1.40 or less, 1.30 or more and 1.38 or less, or 1.30 or more and1.32 or less.

The thickness of the low refractive index layer is 80 nm or more and 150nm or less, more preferably 85 nm or more and 110 nm or less, morepreferably 90 nm or more and 105 nm or less. The thickness of the lowrefractive index layer is preferably larger than the average particlesize of low refractive index particles such as hollow particles.

The thickness of the low refractive index layer is preferably in therange of 80 nm or more and 150 nm or less, 80 nm or more and 110 nm orless, 80 nm or more and 105 nm or less, 85 nm or more and 150 nm orless, 85 nm or more and 110 nm or less, 85 nm or more and 105 nm orless, 90 nm or more and 150 nm or less, 90 nm or more and 110 nm orless, or 90 nm or more and 105 nm or less. It is more preferable thatthe thickness of the low refractive index layer satisfy theabove-described preferred range and the thickness of the low refractiveindex layer be larger than the average particle size of low refractiveindex particles such as hollow particles.

Methods for forming a low refractive index layer can be broadlyclassified into wet methods and dry methods. Examples of the wet methodinclude a method in which a low refractive index layer is formed by asol-gel method using a metal alkoxide or the like; a method in which aresin having a low refractive index, such as fluororesin, is applied toform a low refractive index layer; and a method in which a coatingsolution for forming a low refractive index layer, in which lowrefractive index particles are contained in a resin composition, isapplied to form a low refractive index layer. Examples of the dry methodinclude a method in which particles having a desired refractive indexare selected from low refractive index particles, and a low refractiveindex layer is formed by a physical vapor deposition method or achemical vapor deposition method.

The wet method is superior to the dry method in terms of productionefficiency, suppression of a slanted reflection color phase and chemicalresistance. In the present embodiment, among the wet methods, formationusing a coating solution for forming a low refractive index layer, inwhich low refractive index particles are contained in a binder resincomposition, is preferable for adhesion, water resistance, scratchresistance and reduction of the refractive index. In other words, thelow refractive index layer preferably comprises a binder resin and lowrefractive index particles.

The binder resin of the low refractive index layer preferably comprisesa cured product of a curable resin composition. The ratio of the curedproduct of a curable resin composition to the total binder resin of thelow refractive index layer is preferably 10 mass % or more, morepreferably 30 mass % or more, more preferably 50 mass % or more, morepreferably 70 mass % or more, more preferably 90 mass % or more, mostpreferably 100 mass %.

Examples of the curable resin composition of the low refractive indexlayer include the curable resin compositions exemplified for the layercomprising a metal oxide.

The low refractive index particle preferably comprises one or moreselected from the group consisting of hollow particles and non-hollowparticles. For balancing between low reflection and scratch resistance,it is preferable that one or more selected from the group consisting ofhollow particles be used in combination with one or more selected fromthe group consisting of non-hollow particles.

The material for each of the hollow particle and the non-hollow particlemay be either an inorganic compound such as silica or magnesiumfluoride, or an organic compound, and silica is preferable for reductionof the refractive index, and strength.

The average particle size of hollow silica particles is preferably 50 nmor more and 200 nm or less, more preferably 60 nm or more and 80 nm orless in consideration of optical properties and mechanical strength. Theaverage particle size of the hollow silica particles is preferably inthe range of 50 nm or more and 80 nm or less or 60 nm or more and 200 nmor less as well as in any of the above-described ranges.

The average particle size of the non-hollow silica particles ispreferably 5 nm or more and 100 nm or less, more preferably 10 nm ormore and 20 nm or less, for prevention of aggregation of the non-hollowsilica particles and in consideration of the dispersibility thereof. Theaverage particle size of the non-hollow silica particles is preferablyin the range of 5 nm or more and 20 nm or less or 10 nm or more and 100nm or less as well as in any of the above-described ranges.

The rate of packing of the hollow silica particles in the binder resinincreases and the refractive index of the low refractive index layerdecreases as the content of the hollow silica particles increases. Thus,the content of the hollow silica particles is preferably 100 parts bymass or more, more preferably 150 parts by mass or more, based on 100parts by mass of the binder resin.

On the other hand, if the content of the hollow silica particles withrespect to the binder resin is excessively high, the amount of hollowsilica particles exposed from the binder resin increases, and the amountof the binder resin for bonding the particles decreases. Consequently,the hollow silica particles are likely to be damaged or fall off, andmechanical strength such as scratch resistance, of the low refractiveindex layer tends to be deteriorated. Thus, the content of the hollowsilica particles is preferably 400 parts by mass or less, morepreferably 300 parts by mass or less, based on 100 parts by mass of thebinder resin.

The content of the hollow silica particles based on 100 pars by mass ofthe binder resin is preferably in the range of 100 parts by mass or moreand 400 parts by mass or less, 100 parts by mass or more and 300 partsby mass or less, 150 parts by mass or more and 400 parts by mass orless, or 150 parts by mass or more and 300 parts by mass or less.

If the content of the non-hollow silica particles is low, there may beno influence on an increase in hardness even in the presence of thenon-hollow silica particles in the surface of the low refractive indexlayer. When the non-hollow silica particles are contained in a largeamount, the influence of the variation in shrinkage due topolymerization of the binder resin decreases, so that the asperityoccurring on the low refractive index surface after curing the resin canbe decreased. Thus, the content of the non-hollow silica particles ispreferably 10 parts by mass or more, more preferably 50 parts by mass ormore, more preferably 70 parts by mass or more, more preferably 100parts by mass or more, based on 100 parts by mass of the binder resin.

On the other hand, if the content of the non-hollow silica particles isexcessively high, the non-hollow silica particles are likely to beaggregated, so that a variation in shrinkage of the binder resin occurs,leading to an increase in asperity on the surface. Thus, the content ofthe non-hollow silica particles is preferably 200 parts by mass or less,more preferably 150 parts by mass or less, based on 100 parts by mass orthe binder resin.

The content of the non-hollow silica particles based on 100 parts bymass of the binder resin is preferably in the range of 10 parts by massor more and 200 parts by mass or less, 10 parts by mass or more and 150parts by mass or less, 50 parts by mass or more and 200 parts by mass orless, 50 parts by mass or more and 150 parts by mass or less, 70 partsby mas or more and 200 parts by mass or less, 70 parts by mass or moreand 150 parts by mass or less, 100 parts by mass or more and 200 partsby mass or less, or 100 parts by mass or more and 150 parts by mass orless.

When the hollow silica particles and the non-hollow silica particles arecontained at the above-described respective proportions in the binderresin, the barrier properties of the low refractive index layer can beimproved. It is presumed that the silica particles are uniformlydispersed at a high rate of packing and thus passage of gases and thelike is inhibited.

A cosmetic product such as a sunscreen or a hand cream may comprise alow molecular weight polymer low in volatility. When the low refractiveindex layer has good barrier properties, the low molecular weightpolymer can be inhibited from penetrating into the coating film of thelow refractive index layer, and any failure such as appearanceabnormality due to the long-term remaining of the low molecular weightpolymer in the coating film can be suppressed. Suppression ofpenetration of the low molecular weight polymer into the coating film ofthe low refractive index layer is also preferable for reducing theemissivity α.

<Emissivity>

The emissivity of the optical laminate of the present disclosure forlight with a wavelength range of 2000 nm or more and 22000 nm or less isrequired to be 0.27 or more and 0.75 or less as measured from the sideof the layer comprising a metal oxide with respect to the plastic film.In the present specification, the emissivity is sometimes referred to asan “emissivity α” as described above.

If the emissivity α is more than 0.75, the optical laminate absorbsradiation heat resulting from an external environment such as atemperature of the interior of a vehicle, so that the visibility of animage display device comprising the optical laminate is deteriorated.

If the emissivity α is less than 0.27, radiation heat generated in theimage display device is returned into the image display device by theoptical laminate, so that the inside of the image display device issubjected to high temperature, resulting in deterioration of thevisibility of the image display device comprising the optical laminate.Examples of the radiation heat generated in the image display deviceinclude radiation heat generated from a display element.

The emissivity α is preferably 0.35 or more and 0.70 or less, morepreferably 0.37 or more and 0.67 or less, further preferably 0.40 ormore and 0.60 or less.

With the improvement in display technology in recent years, for example,a flexible optical laminate may be desired for imparting a curvedsurface property to a display to improve the design property. If theemissivity α is less than 0.40, the layer comprising a metal oxide maybe likely to harden, leading to occurrence of a problem in curvedsurface formability. Thus, an emissivity α of 0.40 or more is preferablefor curved surface formability. The emissivity α is preferably as low aspossible because a temperature rise resulting from an externalenvironment can be controlled. Thus, for example, an emissivity α of0.60 or less is preferable in that the sensory temperature when a faceor a hand is kept close to the image display device for a long time canbe easily lowered because the surface temperature of the opticallaminate can be easily made low enough to touch the optical laminatesurface with the hand without difficulty and the optical laminate itselfcan be easily inhibiting from acting as a heat source.

The emissivity α is preferably in the range of 0.27 or more and 0.75 orless, 0.27 or more and 0.70 or less, 0.27 or more and 0.67 or less, 0.27or more and 0.60 or less, 0.35 or more and 0.75 or less, 0.35 or moreand 0.70 or less, 0.35 or more and 0.67 or less, 0.35 or more and 0.60or less, 0.37 or more and 0.75 or less, 0.37 or more and 0.70 or less,0.37 or more and 0.67 or less, 0.37 or more and 0.60 or less, 0.40 ormore and 0.75 or less, 0.40 or more and 0.70 or less, 0.40 or more and0.67 or less, or 0.40 or more and 0.60 or less.

In the present specification, the deterioration of visibility means, forexample, that “various kinds of performance such as lightness, color andreflection direction characteristics are uneven in limited portionswithin the display screen of the image display device”, “the variouskinds of performance are uneven between the vicinity of the center andthe vicinity of an end of the display screen of the image displaydevice” or “the various kinds of performance in a high-temperatureenvironment are different from those in a normal-temperatureenvironment”.

Such deterioration of visibility may occur due to, for example,heat-induced deformation of the optical laminate.

An image display device typically comprises cooling means such as anair-cooling fan, and the cooling effect of the cooling means variesdepending on a location in the image display device. Radiation heat iscontinuously generated, and therefore the aforementioned difference incooling effect is gradually accumulated, so that the temperature variesdepending on a location in the image display device. Thus, within asurface of the optical laminate, there may be portions different intemperature, and in such a case, the optical laminate may undergo alocal change in physical properties, resulting in deterioration ofvisibility.

The optical laminate of the present disclosure is capable of suppressingdeterioration of visibility which is caused as described above.

In the present specification, the emissivity α means an emissivity atnormal temperature which is measured in accordance with JIS A1423:1983.Examples of the apparatus for measuring the emissivity include Model“TSS-5X-2” manufactured by Japan Sensor Corporation.

In the present specification, various physical properties such as anemissivity, a spectral transmittance, a luminous reflectance Y value, atotal light transmittance and a haze are those obtained by exposing ameasurement sample to an environment at a temperature of 23±5° C. and arelative humidity of 40% or more and 65% or less for 30 minutes or more,followed by measurement in the same environment unless otherwisespecified.

In the present specification, various physical properties such as anemissivity, a spectral transmittance, a luminous reflectance Y value, atotal light transmittance and a haze are each determined as an averagevalue of 20 measurements unless otherwise specified.

<Physical Properties>

The average of spectral transmittance of the layer comprising a metaloxide in a wavelength range of 8200 nm or more and 9000 nm or less ispreferably 80% or less, more preferably 70% or less, further preferably60% or less.

The following expression (1) indicates a peak wavelength (λ) of aradiation wavelength emitted by a blackbody at a certain temperature,and is called Wien's equation. In the expression, “T” represents atemperature in the unit of ° C. λ(nm)=2897/(T+273) (1)

For example, the temperatures of the atmosphere of the interior and adashboard of an automobile in the summer and the temperature at thewindow in a closed room in the summer are each said to be about 50° C.or higher and 80° C. or lower. By assigning 50 and 80 to T in the aboveexpression, values of about 9000 nm and about 8200 nm, respectively, areobtained as λ.

That is, the wavelength range for the spectral transmittance isspecified as 8200 nm or more and 9000 or less in consideration of thetemperature of an automobile in the summer and the temperature at thewindow in a closed room in the summer. Thus, when the average of thespectral transmittance is 80% or less, the optical laminate efficientlycuts an infrared ray emitted from the interior of an automobile, andtherefore the image display device can be further inhibited from beingsubjected to high temperature, so that deterioration of visibility canbe more easily suppressed.

The lower limit of the average of the spectral transmittance is notparticularly limited, and is typically 30% or more, preferably 40% ormore.

In the present specification, the spectral transmittance of the layercomprising a metal oxide means a value calculated through the followingmeasurement (A1) and transformation (A2).

(A1) The absorbance of the layer comprising a metal oxide at eachwavelength is measured by reflection in FTIR.(A2) The absorbance at each wavelength in Al is transformed into atransmittance at each wavelength.

The measurement (A1) is performed on the side of the layer comprising ametal oxide with respect to the plastic film. Even in the presence ofthe functional layer β on the layer comprising a metal oxide, themeasurement (A1) can be performed in the presence of the functionallayer β as long as the total thickness of the functional layer β isabout 250 nm or less. The absorbance of the layer comprising a metaloxide, which has been measured in the presence of the functional layerβ, is transformed in (A2). In this way, the spectral transmittance ofthe layer comprising a metal oxide can be calculated.

The luminous reflectance Y value of the optical laminate which ismeasured from the side of the layer comprising a metal oxide withrespect to the plastic film is preferably 2.0% or less, more preferably1.0% or less, further preferably 0.5% or less.

In the present specification, the luminous reflectance Y value refers toa luminous reflectance Y value in the CIE 1931 standard color system,and is determined at an incidence angle of 5 degrees.

The luminous reflectance Y value can be calculated using aspectrophotometer. Examples of the spectrophotometer include trade name“UV-2450” manufactured by Shimadzu Corporation.

It is preferable to bond a black plate to the back surface of theplastic film in measurement of the luminous reflectance.

The JIS K7361-1:1997-specified total light transmittance of the opticallaminate is preferably 70% or more, more preferably 80% or more, furtherpreferably 90% or more.

The JIS K7136-1:2000-specified haze of the optical laminate ispreferably 5% or less, more preferably 3% or less, further preferably 1%or less.

The light incidence surface used for measuring the total lighttransmittance and the haze is preferably a surface on the plastic filmside with respect to the layer comprising a metal oxide.

In the optical laminate, the roughness of an outermost surface on theside of the layer comprising a metal oxide with respect to the plasticfilm is preferably in a predetermined range.

Specifically, the JIS B0601:2001-specified arithmetic average roughnessRa of the outermost surface at a cutoff value of 2.5 mm is preferably 3μm or less, more preferably 1 μm or less, further preferably 0.1 μm orless. When Ra is 3 μm or less, the emissivity α can be easily set to0.75 or less.

When Ra is measured, it is preferable to set the lateral magnificationto 1000 times and set the longitudinal magnification to 20000 times asmeasurement conditions in the measurement apparatus.

<Layer Configuration>

The overall layer structure of the optical laminate of the presentdisclosure is not particularly limited, and examples thereof include thefollowing (1) to (6). It is to be noted that “I” denotes the interfacebetween layers.

(1) plastic film/layer comprising a metal oxide(2) plastic film/hardcoat layer/layer comprising a metal oxide(3) plastic film/layer comprising a metal oxide/low refractive indexlayer(4) plastic film/hardcoat layer/layer comprising a metal oxide/lowrefractive index layer(5) plastic film/layer comprising a metal oxide/high refractive indexlayer/low refractive index layer(6) plastic film/hardcoat layer/layer comprising a metal oxide/highrefractive index layer/low refractive index layer.

<Total Thickness>

The total thickness of the optical laminate is preferably 10 μm or more,more preferably 30 μm or more, further preferably 45 μm or more forobtaining good mechanical strength. For easily applying the opticallaminate to a foldable image display device and a rollable image displaydevice, the total thickness of the optical laminate is preferably 130 μmor less, more preferably 100 μm or less, further preferably 90 μm orless, still further preferably 75 μm or less.

The total thickness of the optical laminate is preferably in the rangeof 10 μm or more and 130 μm or less, 10 μm or more and 100 μm or less,10 μm or more and 90 μm or less, 10 μm or more and 75 μm or less, 30 μmor more and 130 μm or less, 30 μm or more and 100 μm or less, 30 μm ormore and 90 μm or less, 30 μm or more and 75 μm or less, 45 μm or moreand 130 μm, 45 μm or more and 100 μm or less, 45 μm or more and 90 μm orless, or 45 μm or more and 75 μm or less.

When the total thickness of the optical laminate is in any of theabove-described ranges, a value of φ10 mm or less can be easily achievedin evaluation with an outward bending mandrel test bar. An opticallaminate having a total thickness of 75 μm or less, among theabove-described ranges, enables even a value of φ6 mm or less to beeasily achieved. That is, when the total thickness of the opticallaminate is in any of the above-described ranges, the optical laminatecan be easily applied to a foldable image display device and a rollableimage display device. The term “outward bending” means that bending isperformed so that the side of the layer comprising a metal oxide withrespect to the plastic film faces outside. The term “outside” means a“side more remote from the mandrel bar”.

[Polarizing Plate]

The polarizing plate of the present disclosure comprises a polarizer, afirst transparent protection plate disposed on one side of thepolarizer, and a second transparent protection plate disposed on theother side of the polarizer, wherein at least one selected from thegroup consisting of the first transparent protection plate and thesecond transparent protection plate is the above-described opticallaminate of the present disclosure.

<Polarizer>

Examples of the polarizer include a sheet-type polarizer such as apolyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetalfilm, and an ethylene-vinyl acetate copolymer-based saponified filmwhich are dyed with iodine or the like and are stretched, a wiregrid-type polarizer formed from a large number of metal wires arrangedin parallel, a coating-type polarizer coated with a lyotropic liquidcrystal or a dichroic guest-host material, and a multilayer thinfilm-type polarizer. Such a polarizer may be a reflection-type polarizerhaving a function of reflecting a non-transmission polarizing component.

<Transparent Protection Plate>

The first transparent protection plate is disposed on one side of thepolarizer, and the second transparent protection plate is disposed onthe other side. At least one of the first transparent protection plateand the second transparent protection plate is the above-describedoptical laminate of the present disclosure.

The optical laminate is preferably disposed such that a surface on theplastic film side with respect to the layer comprising a metal oxidefaces the polarizer side.

Examples of the first transparent protection plate and the secondtransparent protection plate other than the optical laminate include aplastic film and glass, and a plastic film is preferable.

Examples of the plastic film include a polyester film, a polycarbonatefilm, a cycloolefin polymer film, an acrylic film, and a triacetylcellulose film, and stretched films thereof are preferable for themechanical strength.

It is preferable to bond the polarizer to the transparent protectionplate with an adhesive interposed therebetween. As the adhesive, acommon adhesive can be used, and a PVA-based adhesive is preferable.

In the polarizing plate of the present disclosure, both the firsttransparent protection plate and the second transparent protection platemay be the above-described optical laminate of the present disclosure,and it is preferable that one of the first transparent protection plateand the second transparent protection plate be the optical laminate ofthe present disclosure. When the polarizing plate of the presentdisclosure is used as a polarizing plate disposed on the light emissionsurface of the display element, it is preferable that a transparentprotection plate on the light emission surface of the polarizer be theabove-described optical laminate of the present disclosure.

[Surface Plate for Image Display Device]

The surface plate for an image display device according to the presentdisclosure is one obtained by bonding the above-described opticallaminate of the present disclosure onto a resin plate or a glass plate.

The optical laminate is preferably disposed such that a surface on theplastic film side with respect to the layer comprising a metal oxidefaces the resin plate or the glass plate side.

The surface plate for an image display device is preferably disposedsuch that a surface on the bonded optical laminate side faces thesurface side. In other words, the surface plate for an image displaydevice is preferably disposed such that a surface on the bonded opticallaminate side faces a side opposite to the display element.

As the resin plate or the glass plate, a resin plate or a glass platewhich is commonly used as a surface plate for an image display devicecan be used.

The thickness of the resin plate or the glass plate is preferably 10 μmor more for obtaining good strength. The upper limit of the thickness ofthe resin plate or the glass plate is typically 5000 μm or less, and ispreferably 1000 μm or less, more preferably 500 μm or less, furtherpreferably 100 μm or less because it has been preferred to thin an imagedisplay device in recent years.

The thickness of the resin plate or the glass plate is preferably in therange of 10 μm or more and 5000 μm or less, 10 μm or more and 1000 μm orless, 10 μm or more and 500 μm or less, or 10 μm or more and 100 μm orless.

[Image Display Device]

The image display device of the present disclosure has theabove-described optical laminate of the present disclosure on the lightemission surface of the display element.

The optical laminate is preferably disposed such that a surface on theside of the layer comprising a metal oxide with respect to the plasticfilm faces a side opposite to the display element.

The optical laminate is preferably disposed on an outermost surface ofthe image display device.

For suppressing heat conduction, the optical laminate is preferablydisposed such that air is interposed between the display element and theoptical laminate in the image display device.

Examples of the display element include a liquid crystal displayelement, an EL display element such as an organic EL display element andan inorganic EL display element, a plasma display element, and a LEDdisplay element such as a micro LED display element and a mini LEDdisplay element. These display elements may have a touch panel functionin the display element.

Examples of the liquid crystal display mode of the liquid crystaldisplay element include IPS mode, VA mode, multi-domain mode, OCB mode,STN mode, and TSTN mode. When the display element is a liquid crystaldisplay element, a backlight is required. The backlight is disposed onthe liquid crystal display element, the back light being on a sideopposite to the optical laminate.

The image display device may be a foldable image display device or arollable image display device. The image display device may be an imagedisplay device with a touch panel.

A portable image display device and an image display device installed ina dashboard of an automobile are preferable in that the effects of thepresent disclosure are easily exhibited because the image displaydevices are likely to be exposed to a high-temperature environment.

The image display device preferably has a common heat dissipationmechanism on the display element, the heat dissipation mechanism beingon a side opposite to the light emission surface. Examples of the commonheat dissipation mechanism include an air-cooling fan, a heatdissipation fin, a heat pump, and a Peltier element.

EXAMPLES

Hereinafter, the present disclosure will be described in detail byshowing Examples and Comparative Examples. The present disclosure is notlimited to forms described in Examples.

1. Evaluation and Measurement

The optical laminates obtained in Examples and Comparative Examples weremeasured and evaluated in the following manners. Table 1 shows theresults. Unless particularly denoted, the atmosphere in each measurementand evaluation was at a temperature of 23±5° C. and a relative humidityof 40% or more and 65% or less, and a specimen of interest was exposedto the atmosphere for 30 minutes or more before the start of eachmeasurement and evaluation, and then subjected to measurement andevaluation.

The optical laminate of Comparative Example 2 does not have a layercomprising a metal oxide. Thus, for Comparative Example 2, the followingevaluations and measurements are performed with the heat dissipationlayer of Comparative Example 2 likened to the layer comprising a metaloxide.

1-1. Emissivity

For the optical laminates of Examples and Comparative Examples, theemissivity at normal temperature was measured in accordance with JISA1423:1983. Specifically, “the emissivity of the optical laminate forlight with a wavelength range of 2000 nm or more and 22000 nm or lesswas measured from the side of the layer comprising a metal oxide withrespect to the substrate”. In the present specification, the emissivityis sometimes referred to as an “emissivity α” as described above.

A specimen having an emissivity α of more than 0.75 was rated C. Aspecimen having an emissivity α of less than 0.27 was rated B. Aspecimen having an emissivity α of 0.27 or more and 0.75 or less wasrated A or higher, and in particularly, a specimen having an emissivityα of 0.37 or more and 0.60 or less was rated AA.

If the emissivity α is excessively high, the temperature of the imagedisplay device rises because the optical laminate absorbs radiation heatresulting from an external environment. On the other hand, if theemissivity α is excessively low, the optical laminate is less likely toabsorb radiation heat resulting from an external environment, but theinside of the image display device may be subjected to high temperaturebecause the radiation heat generated in the image display device isreturned into the image display device by the optical laminate.

Model “TSS-5X-2” manufactured by Japan Sensor Corporation was used as anemissivity measurement device. There are two types of emissivityreference pieces attached to the measurement device, where one has anemissivity of 0.06 and the other has an emissivity of 0.97. The mainspecs of the measurement device are as follows.

<Specs>

Measurement area: φ15 mmMeasurement distance: 12 mm

1-2. Spectral Transmittance

For the optical laminates of Examples and Comparative Examples, thespectral transmittance of the layer comprising a metal oxide in awavelength range of 8200 nm or more and 9000 nm or less was measured. Asdescribed in the text of the specification, the absorbance of the layercomprising a metal oxide at each wavelength was measured by reflectionin FTIR, and the absorbance at each wavelength was then transformed intoa transmittance at each wavelength to calculate the spectraltransmittance of the layer comprising a metal oxide in a wavelengthrange of 8200 nm or more and 9000 nm or less.

As the FTIR measurement device, Model “NICOLET iS10” manufactured byThermo Fisher Scientific was used. As an accessory, “Single ReflectionType Ge ATR Accessory Foundation” manufactured by the same company asabove was used. For the measurement conditions, the specimen waspressure-bonded and fixed to a pressure tower with the measurementsurface facing the Ge crystal surface, and the measurement was thenperformed under the following conditions: incidence type: single and45°; number of scans: 32; resolution: 8; detector: DTGS KBr; mirrorspeed: 0.6329; aperture: open; and measurement range: 680 cm⁻¹ or moreand 4000 cm⁻¹ or less. The measured absorbance was transformed into atransmittance, and a value in cm⁻¹ was transformed into a value in nm tocalculate an average value of transmittances in the wavelength range.

1-3. Luminous Reflectance Y Value

A specimen was prepared by bonding a black plate (trade name: COMOGLASDFA2CG 502K (black) type manufactured by KURARAY CO., LTD., thickness: 2mm) to the substrate of the optical laminate of each of Examples andComparative Examples so as to locate the black plate on a side oppositeto the layer comprising a metal oxide, with a 25 μm-thick transparentpressure sensitive adhesive layer (trade name: PANACLEAN PD-S1manufactured by PANAC Co., Ltd.) interposed between the black plate andthe substrate. The luminous reflectance Y value was measured with lightbeing incident to the specimen at an incidence angle of 5 degrees fromthe side of the layer comprising a metal oxide with respect to thesubstrate.

The luminous reflectance Y value was determined as a value representinga luminous reflectance obtained by measuring a 5° regular reflectanceunder the conditions of a viewing angle of 2 degrees, a C light sourceand a wavelength range of 380 nm or more and 780 nm or less by use of aspectral reflectometer (trade name: UV-2450 manufactured by ShimadzuCorporation), and thereafter performing calculation by software (UVPCcolor measurement Version 3.12 built in apparatus) for conversion intobrightness sensed by human eyes.

1-4. Total Light Transmittance and Haze

The JIS K7361-1:1997-specified total light transmittance and the JISK7136:2000-specified haze of the optical laminate of each of Examplesand Comparative Examples were measured by use of a haze meter (HM-150manufactured by Murakami Color Research Laboratory Co., Ltd.). The lightincidence surface was on the substrate side.

1-5. Surface Temperature

A simulated liquid crystal display device was prepared by disposing theoptical laminate of each of Examples and Comparative Examples on acommercially available liquid crystal device (trade name: Kindle FireHDX from Amazon.com, Inc.) such that the substrate of the opticallaminate faced the display device.

For simulating the interior of an automobile in the summer, thesimulated liquid crystal display device was placed in an oven at 80° C.,and taken out after 10 minutes. Immediately after the simulated liquidcrystal display device was taken out, the temperature was measured fromthe surface side by an IR camera (trade name: FLIR E4 manufactured byFLIR Systems, Inc.). The distance between the optical film and the IRcamera was 30 cm. Table 1 shows the maximum temperatures of the tops ofthe optical laminates. A maximum temperature of 65° C. or lowercorresponds to an acceptable level. In consideration of an actualsituation of image display, the maximum temperature is more preferably60° C. or lower, further preferably 57° C. or lower.

1-6. Visibility (Unevenness)

The simulated liquid crystal display device prepared in 1-5 was placedin an oven at 80° C., and taken out after 10 minutes. Immediately afterthe simulated liquid crystal display device was taken out, the entirescreen of the liquid crystal display device was shown in green color,and whether or not there were portions uneven in lightness and color wasvisually evaluated. Ten persons having a vision of 0.7 or more served asevaluators. The vision includes a corrected vision. The distance betweenthe evaluator and the liquid crystal display device was 50 cm. Aspecimen for which eight or more of the persons indicated that therewere not portions uneven in lightness and color was rated “A”, and aspecimen for which seven or less of the persons indicated that therewere not portions uneven in lightness and color was rated “C”.

2. Preparation of Optical Laminate Example 1

The following coating solution for a hardcoat layer was applied onto asubstrate (triacetyl cellulose film, thickness: 60 μm), dried, andirradiated with an ultraviolet ray to form a 5 μm-thick hardcoat layeron the substrate.

Subsequently, the following coating solution 1 for a metal oxide layerwas applied onto the hardcoat layer, dried, and irradiated with anultraviolet ray to form a 350 nm-thick layer comprising ITO particles asmetal oxide particles on the hardcoat layer.

Subsequently, the following coating solution for a low refractive indexlayer was applied onto the layer comprising a metal oxide, dried, andirradiated with an ultraviolet ray to form a 100 nm-thick low refractiveindex layer on the layer comprising a metal oxide, thereby obtaining anoptical laminate of Example 1.

<Coating Solution for Hardcoat Layer>

The following components were mixed to prepare a hardcoat layer formingcomposition.

Pentaerythritol triacrylate 46 parts by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)Photopolymerization initiator 4 parts by mass(trade name: Omnirad 184 from IGM Resins B.V. Company)Methyl ethyl ketone 50 parts by mass

<Coating Solution 1 for Metal Oxide Layer>

The following components were mixed to prepare a coating solution 1 fora metal oxide layer.

Pentaerythritol triacrylate 1 part by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)ITO particles 8.5 parts by mass(average particle size: 30 nm)Photopolymerization initiator 0.4 parts by mass(trade name: Omnirad 184 from IGM Resins B.V. Company)Leveling agent 0.03 parts by mass(MEGAFAC F-477 manufactured by DIC Corporation)Methyl isobutyl ketone 89 parts by mass

<Coating Solution for Low Refractive Index Layer>

The following components were mixed to prepare a coating solution for alow refractive index layer.

Pentaerythritol triacrylate 0.4 parts by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)Fluorine-containing polymer 0.2 parts by mass (solid content)(trade name: JN35 manufactured by JSR Corporation)Fluorine-containing monomer 0.7 parts by mass (solid content)(trade name: LINC 3A manufactured by KYOEISHA CHEMICAL Co., LTD.)Hollow silica articles 1.7 parts by mass(average particle size: 75 nm and refractive index: 1.212)Solid silica particles 0.6 parts by mass(average particle size: 15 nm)Leveling agent 0.06 parts by mass(trade name: X-22-164E from Shin-Etsu Silicone)Photopolymerization initiator 0.09 parts by mass(trade name: Omnirad 127 from IGM Resins B.V. Company)Solvent 97 parts by mass(mixed solvent of methyl isobutyl ketone and propylene glycol monomethylether acetate at a mass ratio of 70:30, prepared on the basis of athickness with a solid content of 2 mass %)

Example 21

Except that the thickness of the layer comprising a metal oxide waschanged to 700 nm, the same procedure as in Example 1 was carried out toobtain an optical laminate of Example 2.

Example 31

Except that the thickness of the layer comprising a metal oxide waschanged to 200 nm, the same procedure as in Example 1 was carried out toobtain an optical laminate of Example 3.

Example 4

Except that the substrate (triacetyl cellulose film, thickness: 60 μm)was changed to a 100 μm-thick biaxially stretched polyethyleneterephthalate film, the same procedure as in Example 1 was carried outto obtain an optical laminate of Example 4.

Example 5

Except that for the layer comprising a metal oxide, the coating solution1 for a metal oxide layer was changed to the following coating solution2 for a metal oxide layer, and the thickness was changed to 900 nm, thesame procedure as in Example 1 was carried out to obtain an opticallaminate of Example 5.

<Coating Solution 2 for Metal Oxide Layer>

Pentaerythritol triacrylate 1 part by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)Al doped ZnO particles 9.6 parts by massPhotopolymerization initiator 0.4 parts by mass(trade name: Omnirad 184 from IGM Resins B.V. Company)Leveling agent 0.03 parts by mass(MEGAFAC F-477 manufactured by DIC Corporation)Methyl isobutyl ketone 89 marts by mass

Example 6

The coating solution 1 for a metal oxide layer was changed to thefollowing coating solution 3 for a metal oxide layer, and the thicknessof the layer comprising a metal oxide was changed to 900 nm. Further, astep of performing heating at 100° C. for 60 minutes was added after thecoating solution for a metal oxide layer was applied, dried, andirradiated with an ultraviolet ray. Except for the aforementionedchanges and additions, the same procedure as in Example 1 was carriedout to obtain an optical laminate of Example 6.

Example 7

The coating solution for a hardcoat layer was applied onto a substrate(cycloolefin polymer film, thickness: 47 μm), dried, and irradiated withan ultraviolet ray to form a 5 μm-thick hardcoat layer on the substrate.

Subsequently, the following coating solution 3 for a metal oxide layerwas applied onto the hardcoat layer, dried, and irradiated with anultraviolet ray to form a 900 nm-thick layer comprising ITO particles asmetal oxide particles on the hardcoat layer, and heating was thenperformed at 150° C. for 60 minutes.

Subsequently, the coating solution for a low refractive index layer wasapplied onto the layer comprising a metal oxide, dried, and irradiatedwith an ultraviolet ray to form a 100 nm-thick low refractive indexlayer on the layer comprising a metal oxide, thereby obtaining anoptical laminate of Example 7.

<Coating Solution 3 for Metal Oxide Layer>

The following components were mixed to prepare a coating solution 3 fora metal oxide layer.

Pentaerythritol triacrylate 0.5 parts by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)ITO particles 9 parts by mass(average particle size: 30 nm)Photopolymerization initiator 0.4 parts by mass(trade name: Omnirad 184 from IGM Resins B.V. Company)Leveling agent 0.03 parts by mass(MEGAFAC F-477 manufactured by DIC Corporation)Methyl isobutyl ketone 89 marts by mass

Example 8

On a substrate (100 μm-thick biaxially stretched polyethyleneterephthalate film), a hardcoat layer was formed in the same manner asin Example 1.

Subsequently, a 130 nm-thick metal oxide film was formed on the hardcoatlayer by performing sputtering using an ITO target while introducingargon mixed with oxygen gas. The ITO target comprises indium and tin ata mass ratio of 90:10. The metal oxide film is an amorphous film of ITO.

Subsequently, a surface of the metal oxide film was subjected to coronadischarge treatment, and the same low refractive index layer as inExample 1 was then formed on the metal oxide film to obtain an opticallaminate of Example 8.

Comparative Example 1

A 140 nm-thick metal oxide film was formed on a 0.7 mm-thick glasssubstrate by performing sputtering using an ITO target while introducingargon mixed with oxygen gas. The ITO target comprises indium and tin ata mass ratio of 90:10. Subsequently, the metal oxide film was heated at200° C. for 30 minutes to be subjected to annealing treatment, therebyobtaining an optical laminate of Comparative Example 1 in which a 140nm-thick crystal film of ITO is present on a glass substrate.

Comparative Example 2

The following coating solution for a heat dissipation layer was appliedonto a substrate (triacetyl cellulose film, thickness: 60 μm), dried,and irradiated with an ultraviolet ray to form a 1 μm-thick heatdissipation layer, thereby obtaining an optical laminate of ComparativeExample 2.

<Coating Solution for Heat Dissipation Layer>

The following components were mixed to prepare a coating solution for aheat dissipation layer.

Pentaerythritol triacrylate 3.2 parts by mass(trade name: KAYARAD PET-30 from Nippon Kayaku Co., Ltd.)Boron nitride particles 6.4 parts by mass(average particle size: 700 nm)Photopolymerization initiator 0.4 parts by mass(trade name: Omnirad 184 from IGM Resins B.V. Company)Methyl ethyl ketone 90 parts by mass

TABLE 1 Comparative Example Example 1 2 3 4 5 6 7 8 1 2 Emissivity α0.70 0.60 0.73 0.67 0.72 0.43 0.38 0.30 0.22 0.88 Spectral 70 60 72 6570 50 34 78 91 90 transmittance (%) Y value (%) 0.3 0.4 0.3 0.5 0.8 0.40.4 0.4 5.7 — Total light 94 93 95 94 91 93 92 94 86 89 transmittance(%) Haze (%) 0.6 0.8 0.6 0.8 1.0 0.9 0.9 0.3 0.2 18.9 Evalu- EmissivityA AA A A A AA AA A B C ation α Surface 60 56 63 59 61 51 44 45 37 70temperature (° C.) Visibility A A A A A A A A C C

From the results in Table 1, it can be confirmed that the opticallaminate of the present disclosure is capable of suppressingdeterioration of visibility in a high-temperature environment.

A mandrel test was conducted on the optical laminates of Examples 1 to 8in accordance with JIS K5600-5-1:1999. Specifically, a test piece of 100mm×25 mm was cut out from the optical laminate of each of Examples 1 to8, and wound around a mandrel bar such that the short sides of the testpiece were parallel to the mandrel bar. The test piece was wound aroundthe mandrel bar in a state of being bent outward. As the mandrel bar,mandrel bars of φ10 mm and φ6 mm were used.

The results of the mandrel tests described above showed that at φ10 mm,the optical laminates of Examples 1 to 8 had no cracks in the layercomprising a metal oxide and the low refractive index layer. Even at φ6mm, the optical laminates of Examples 1 to 3 and 5 to 7 had no cracks inthe layer comprising a metal oxide and the low refractive index layer.From these results, it can be said that the optical laminates ofExamples 1 to 8 have good flex resistance, and is easily applied to afoldable image display device and a rollable image display device. Itcan also be seen that among the optical laminates of Examples, those ofExamples 1 to 3 and 5 to 7 have extremely good flex resistance.

REFERENCE SIGNS LIST

-   10: Plastic film-   20: Functional layer a-   21: Hardcoat layer-   30: Layer comprising a metal oxide-   40: Functional layer (3-   41: Low refractive index layer-   100: Optical laminate

1. An optical laminate, comprising a layer comprising a metal oxide on aplastic film, wherein an emissivity of the optical laminate for lightwith a wavelength range of 2000 nm or more and 22000 nm or less is 0.27or more and 0.75 or less as measured from a side of the layer comprisinga metal oxide with respect to the plastic film.
 2. The optical laminateaccording to claim 1, wherein an average of spectral transmittance ofthe layer comprising a metal oxide in a wavelength range of 8200 nm ormore and 9000 nm or less is 80% or less.
 3. The optical laminateaccording to claim 1, wherein the layer comprising a metal oxidecomprises metal oxide particles as the metal oxide, and a binder resin.4. The optical laminate according to claim 3, wherein the metal oxideparticles comprise indium tin oxide particles.
 5. The optical laminateaccording to claim 1, comprising at least one functional layer α betweenthe plastic film and the layer comprising a metal oxide.
 6. The opticallaminate according to claim 5, comprising a hardcoat layer as thefunctional layer α.
 7. The optical laminate according to claim 1,comprising at least one functional layer β0 on the layer comprising ametal oxide, side opposite to the plastic film.
 8. The optical laminateaccording to claim 7, wherein a total thickness of the at least onefunctional layer β is 1000 nm or less.
 9. The optical laminate accordingto claim 7, comprising a low refractive index layer as the functionallayer β.
 10. The optical laminate according to claim 1, wherein aluminous reflectance Y value of the optical laminate is 2.0% or less asmeasured from the side of the layer comprising a metal oxide withrespect to the plastic film.
 11. A polarizing plate comprising: apolarizer; a first transparent protection plate disposed on one side ofthe polarizer; and a second transparent protection plate disposed on theother side of the polarizer, wherein at least one selected from thegroup consisting of the first transparent protection plate and thesecond transparent protection plate is the optical laminate according toclaim
 1. 12. A surface plate for an image display device, comprising theoptical laminate according to claim 1 bonded onto a resin plate or aglass plate.
 13. An image display device comprising the optical laminateaccording to claim 1 on a light emitting surface side of a displayelement.